1. Field of the Invention
The present invention relates to a method and a device for coupling spectacles and clip-on sun-shades with each other, and more particularly, the present invention relates to a method and a device for coupling spectacles and clip-on sun-shades with each other, which enable sunglasses referred to as "clip-on sun-shades" not having arms to be detachably coupled to spectacles.
2. Description of the Related Art
Generally, spectacles are used for the purpose of enhancing eyesight of a person who has defective vision. Sunglasses help to protect the eyes from strong light which may cause damage to the eyes. Ordinary spectacles comprise lens frames connected together at their inner ends by a nose frame, lenses fitted into respective lens frames, and arms mounted to outer ends of the lens frames through hinges.
Eyesight is divided into normal eyesight, nearsightedness, farsightedness and astigmatism. If incoming parallel lights are imaged such that an image is focused in front of the retina, nearsightedness (myopia) exists, whereby an observer can properly view close objects, but poorly view distant objects. By utilizing concave lenses as lenses of spectacles, nearsightedness can be adequately corrected. If incoming parallel lights are imaged such that an image is focused behind the retina, farsightedness (hyperopia) exists, whereby an observer can poorly view close objects, but properly view distant objects. In the case of astigmatism, due to the fact that a spherical surface of the eyeball, especially the cornea, is not even, incoming parallel lights cannot be focused directly to a point on the retina, whereby an observer cannot properly focus his eyesight.
While, as described above, spectacles are used for enhancing eyesight of a person who has defective vision, in a hot summer weather when ultraviolet rays dominate, a spectacle wearer must prepare separate sunglasses.
In other words, unlike non-prescription sunglasses which are worn by persons who do not have vision defects, in the case of persons who wear spectacles due to an ocular refractive error, separate sunglasses having vision-corrective lenses of a power which corresponds to that of the user's normal spectacle lenses, must be used, whereby cost is increased.
To cope with this problem, clip-on sun-shades which do not have arms and to which tinted lenses are mounted, are attached in front of the spectacles, thereby to render the same vision enhancing effect as can be achieved by wearing the conventional vision-corrective sunglasses having arms.
Referring to FIG. 9, there is shown a cross-sectional view illustrating a state wherein spectacles and clip-on sun-shades according to the conventional art are coupled with each other. The spectacles 10 has first lens frames 2 which are connected together at their inner ends by a first nose frame 3, lenses 1 which are fitted into respective first lens frames 2, and arms 4 which are mounted to outer ends of the first lens frames 2 through hinges 5. The clip-on sun-shades 20 have second lens frames 22 which are connected together at their inner ends by a second nose frame 23, and tinted lenses 21 which are fitted into respective second lens frames 22.
In order to couple the spectacles 10 and the clip-on sun-shades 20 with each other, the first nose frame 3 of the spectacles 10 and the second nose frame 23 of the clip-on sun-shades 20 are formed with accommodating grooves 25 and 26, respectively, and permanent magnets 27 and 28 are inserted into the accommodating grooves 25 and 26, respectively, whereby the clip-on sun-shades 20 are stably coupled to the spectacles 10 by virtue of magnetic force of the permanent magnets 27 and 28.
However, the above-described coupling structure between the spectacles 10 and the clip-on sun-shades 20 suffers from defects in that, since the accommodating grooves 25 and 26 for receiving the permanent magnets 27 and 28 must be defined in the spectacles 10 and the clip-on sun-shades 20, respectively, sizes of the first and second nose frames 3 and 23 are enlarged, and limitations are imposed on design freedoms for the spectacles 10 and the clip-on sun-shades 20. Moreover, due to weight of the first and second nose frames 3 and 23 and the permanent magnets 27 and 28 which have enlarged sizes, the entire weight of the combination including the spectacles 10 and the clip-on sun-shades 20 is increased, and wearing comfortableness is deteriorated.
In addition, due to the fact that the permanent magnets 27 and 28 should be mounted to the first and second nose frames 3 and 23 of the spectacles 10 and the clip-on sun-shades 20, respectively, assembling operations must be carefully performed while paying attention to directional characteristics of the permanent magnets 27 and 28 depending upon magnetic poles, whereby assemblability is degraded and productivity is diminished. In the worst case, if the permanent magnets 27 and 28 are misassembled, it is impossible to couple the clip-on sun-shades 20 to the spectacles 10.
In particular, as shown in FIG. 10 which is a view illustrating magnetic flux distribution between the spectacles 10 and the clip-on sun-shades 20, in the case that the spectacles 10 and the clip-on sun-shades 20 are coupled with each other using the pair of permanent magnets 27 and 28, the North and South poles N and S of the permanent magnets 27 and 28, which adjoin to each other, are properly coupled with each other by attractive force generated therebetween. However, because magnetic force which is generated in the North and South poles N and S of the permanent magnets 27 and 28, which are opposed to each other is maintained in an opened status, the magnetic force is dissipated and lost to the outside, whereby coupling force between the spectacles 10 and the clip-on sun-shades 20 is remarkably reduced.